Production of substituted succinic anhydrides



` NQV. 19, 1946. M, A K|5E ErAL 2,411,215

PRODUCTION OF SUBSTITUTED SUCCINIC ANHYDRIDES ffy @leed ATTORNEY Nov. 19, 1946.

@my am fied l Refer/w? 1 PRODUCTION OF SUBSTITUTED SUCCINIC ANHYDRIDES M. A. KISE ET AL Filled Jan. 14, 1943 2 'Sheets-Sheet 2 fgoaraar T (bm/enfer iff l Bymlou (ULZJZA temperatures of Patented Nov. 19, 1945 rRoDUcTroN oF SUBS TITU'rEn sUocnvTc ANHYnRmEs Mearl A. 'Klse and Robert F. Engle, Syracuse,

N. Y., assignors to The Solvay Process Company, New York, N. Y., a corporation of New York Application January 14, 1943, Serial No'. 472,350

4 claims.

This invention relates to improvements in the manufacture of alkenyl succinic anhydrides.

Alkenyl succinic4 anhydrides may be synthe- .sized by reacting toge'ther maleic anhydride and aliphatic mono-olens such as those derived from petroleum hydrocarbons by cracking processes. In accordance with well known chemical laws it is desirable to employ relatively high reaction about from 200 C. to 275 C., and pressure sufcient to maintain the oleflns in the liquid phase atthe reaction temperature in order to carry' out the reaction rapidly. vEfiectng the synthesis byV merely mixing olenic cracked petroleum fractions with maleic anhydride and heating the mixture results in formation of substantial amounts of gum in the autoclave during the reaction, with resultant waste of reactants. Further, in carrying out the reaction, dangerous increases in pressure are prone to occur, which increases are attributable to side reactions, particularly decomposition of maleic anhydride, within the reaction zone.

It is an object of this invention to provide an improved process for the synthesis of alkenyl succinicanhydrides from aliphatic mono-olelns and maleic anhydride with materially reduced gum formation and more efcient utilization of maleic anhydride.

It. is a further object of the invention to provide a process for reacting maleic anhydride with mixtures of aliphatic mono-oleflns, such as those derived from petroleum hydrocarbons bycracking processes,'smoothly and rapidly at relatively high temperatures Without dangerous increases in pressure. yOther objects and' advantages will appear hereinafter.

In accordance with the invention, maleic anl-hydridev is dissolved in aliphatic mono-olen mixtures, such as olefinic mixtures of cracked petroleum origin, free from gums and oxygen compounds, under conditions such that substantial reaction of the anhydride With the olens does not occur and when dissolution of the maleic anhydride is complete, the reaction is carried out relatively rapidly at a temperature above 200 C.,

, preferably from 225 to 250 C. under sumcient pressure to maintain the olefins in the liquid phase. Ordinarily, a temperature of from 150 to 200 C. promotes dissolution of the maleic anhydride in the oleiins at a satisfactory rate, i. e., a rate such that complete dissolution of the anhydride is effected within from 0.5 to 2 hours; at these temperatures reaction between the anhydride and olelns proceeds to only a small extent during such period. In order to eiect complete (Cl. 26o-342.4)

dissolution of the maleic anhydride, the reaction mixture should contain at least 80 per cent, pref-.

erably 80 to 95 per cent by weight of hydrocarbons and not more than 20 per cent, preferably 5 to 20 per cent, by Weight of the anhydride. The invention is advantageous chiey in reacting maleic anhydride with olenic cracked petroleum distillate containing oleiinic hydrocarbons boiling within the range of 50 to4 200 C. and having from 4 to12 carbon atoms per molecule but may also bautilized to good effect in connection with higher boiling olen fractions containing up to 25 carbon atoms per molecule.

The use of oleiinic mixtures substantially free from gums and oxygen compounds is an important feature of the invention.' Oleflnic mixtures -contain substantial-amounts of highly reactive material such as di-oleflns which react relatively quickly to form gums and oxygen!I compounds when the mixtures are stored. We have discovered that such reaction products promote the ,formation of relatively large amounts of gum mation of gum and oxygen compounds, the formation of gums during the reaction is greatly reduced. 'For' example, the amount of gums formed when using freshly distilled olenicmixtures in laccordance with the invention, ordinarily doesV not exceed 2 per cent based onthe weightof the reaction mixture while use of olenicfm'ixtures which have been stored until substantial formaition of gums and oxygen compounds takes place production during the y v frequently results in the more of gummy material. Thus the invention substantially reduces waste of olens and maleic anhydride.

By completely dissolving the maleic anhydride to form a substantially homogeneous solution thereof in theolen mixture prior to raising ythe temperature of the mixture to the point where the reaction proceeds rapidly, i; e., abpve ,about 200 C., be carried out rapidly and smoothlywithcut `excessive maleic anhydride `decomposition and waste, accompanied by large increases in pressure, such as have been experienced in reacting undissolved maleic anhydride with olefin mixtures. It may be noted that the reactionbetween olens and maleic4 anhydride proceeds very slowly at temperatures of 150 to 200 C.

it has been found that the reaction may earners l i 3 employed in the dissolution 'step so that the reaction does not proceed to substantial extent, i. e., less-than from to 20 per cent ofthe maleic anhydride is consumed, while effecting dissolution. On the other hand, when the tern perature is raised above 200 C., 50 to 90 per cent or more yof the maleic anhydride is consumed condensing the fractionated olein vapors,v andv 5 is a receiver for the condensed olelns. Condenser fi may be operated at a temperature sumclently low to condense only hydrocarbons of the desired boiling point and receiver 5 may be provided with any suitable means such as valved outlet 6 for discarding uncondensed olelns of lower boiling point. quently inthe process may also be introduced into receiver 5 through valved conduit 0 as will fbe described later. Receiver 5 discharges through valved line; 'H into autoclave u equipped with heating jacket 9. Molten maleic anhydride `from any suitable source is introduced into the `autoclave through valved conduit il. Within the autoclave is"mounted a gear pump i2, having an inlet i3 and an outlet lli, supported by drive shaft it extending through the upper/end ofthe autoclave. The'pump shaft may advantageously be oi hollow construction for circulation therein of cooling liquid such as water.

Reference numeralv i8 designates avalved outlet for `gum formed in the autoclave during "the reaction and is a valved conduit through which the reaction mixture passes from the autoclave through condenser 2l to flash evaporator 22 which distills therefrom unreacted maleic anhydride and hydrocarbons. 'I'he flash evaporator is preferably of the continuous iilm type in which alm of the reaction mixture flows downwardlyyover a heated surface while the more volatile components `of the mixture are vaporized. The. vapors are` condensed in the condenser 24 .and the maleic anhydride is ref moved at 26 for re-use; by maintaining the condensate 'from-condenser 24 at about 55 C., i. e.,

above the melting point of maleic anhydride, the

vanhydride may readily be drawn oi at-26 in molten condition.y The olenic hydrocarbons containing'. some f dissolved maleic anhydride pressure fand the' relatively pure alkenyl succinic anhydride Vvvapors .condensed and recovered in condenser 332. j

Figure`v -2 shows an arrangement for continuous I synthesis ofalkenyi succinic anhydrides. -In this i-lgure reference numeral t5 designates a reservoir for olehns which is supplied with freshly distilled olen stocir from a still such as still l of Figure 1 and with recycled olens which are re- Oleflns recovered subsecovered from the reaction product as described hereinafter. Si is a reservoir for molten maleic anhydride and the anhydride and olen mixture are p ped by pumps 00 through conduits 38 and 30 into coil da' of dissolver di. The coil is of about the same diameter as conduits 00 and 39. The dissolver and coil are jacketed to'per-1 mit maintenance of a temperature of from 150 to 200 C., preferably 3.75" to 200 C. therein. The dissolver may be equipped with any suitable f stirrer for promoting circulation of the olens and the maleic anhydride therein, e. g., a pump 03 having an inlet iii and outlet i5 identical with Ithe gearpump i2 of Figure i. The maleic an-v hydride is substantally completely dissolved in the oleflns during passage through the heated coil 30' and during circulation in the dissolver.' The dissolver is equipped at the bottom with a valved outlet si through which the small gum deposits which form may be removed from time.

may be provided from end to end with'a'spiral member 52 defining a spiral path through which the reaction mixture passes in order to minimize mixing of contents of the reactor lengthwise thereof. Alternatively. the reactor may be constructed as a. series'of pipes of relatively small diameter, e. g.. 0.25 to 2 inches, mounted in tube "sheets in a shell 'equipped with headers at each end, the shell containing heating liquid surrounding the tubes. The reactor continuously discharges through outlet 5B into a flash evaporator 56 which vaporizes unreacted hydrocarbons and maleic anhydride.

These vapors are condensed. in condenser 58, separated in separator 60 and the maleic anhydride recycled to maleic anhydride receiver 3l through conduit ylil. Separatorl 607and conduit 64 are preferably maintained at a temperature above the melting point of maleic anhydride. say yabout 55 C., so-that the anhydride may be circulated in molten' condition. A portion of the hydrocarbons may be continuously bled ofi and discarded at 63 and the remainder recycled to reservoir 35 through conduit-62; a substantial portion of the maleic, anhydride dissolved in the discarded hydrocarbons may be recovered by A cooling the hydrocarbons toabout 15 C. to

crystallize the anhydride and separating the crystals byv filtration. The crude reaction product from the flash evaporator 56 is conducted to still 66 which communicates with condenser 61, a second fractlonating still 68 and condenser 10.' The stills and condensers are operated under reduced lpressure,.e. g., pressure of 10 to 30 mm. of mercury or less. The alkenyl succinic anhydrides are vaporized in still 66 leaving the higher i boiling reaction products as residue and the dis# tillate is condensed in condenser 61. yThe condensate is refractionated in still 68 to separate the more volatile materials including some maleic anhydride and oleiln vapors from the alkenyl succinic anhydrides. which remain as residue. Vapors from still 68 are cooled to about 0 C. in condenser 10 to 4condense the maleic anhydride. and oleins which` are then separated from the non-condensable gases in separator 'l2 and pumped by pump 14 to separator 60 for recirculation to reservoirs 35 and 37. The presence of olens and maleic anhydride `in the vapors from still 68 is due chiey to decomposition of the residues in still 66. It will be appreciated that the batch system of Figure 1 may include an arrangement such as elements. 10, 12 and 'I4 for recovery of maleic anhydride and oleflns evolved during distillation of the alkenyl succinic anhydrides. i

The following examples are illustrative of the invention:

Example 1 .bidity to the distillate the hydrocarbon was ltered to remove emulsiiied water and fractionation was continued. A fraction boiling within the range of80 to 100 C. comprising about 81 per cent by Weight of aliphatic mono-olens containing from 6 to 8 and an average of about 6.8 carbon atoms per molecule, andthe remainder chiey paraiiins and di-olefins was collected. About 102 parts by weight of this freshly distilled fraction and about 18 parts. by weight of molten maleic anhydride were charged into the autoclave 9 to produce therein a mixture con-v taining about per cent by weight of maleic anhydride and about 85 per cent of hydrocarbons. The mixture was-heated in the autoclave to 175 C. for one hour while operating the pump I2 to circulate the hydrocarbons and maleic an- 4 hydride; complete dissolution of the maleic anhydride'in the hydrocarbons was effected during this period. Separation of the hydrocarbons and maleic anhydride into layers during the dissolution and reaction periods tends to promote gum formation. Circulation of the mixture during these periodsnot only promotes dissolution but prevents the formation of such layers.

The temperature in the autoclave was then raised to 225 C. and maintained at this point for two hours, i. e., until about 90 percent of the maleic anhydride present in the autoclave charge was consumed. VThe autoclave was maintained under 275 pounds of pressure per square inch during the dissolution and reaction periods, i. e., under suicient pressure to maintain the reactants in the liquid phase. The gum formed during the reaction settled to the bottom of thev autoclave and was removed through valved out- 4let I8. The remainder of reaction mixture was' then emptied from the autoclave through condenser 2| which cooled the mixture sullciently to maintain the hydrocarbons and the maleic anhydride in the liquid phase. The mixture was f passed to flash evaporator 22 where the unreacted hydrocarbons and maleic anhydride were driven off, condensed in condenser 24 and sepa rately collected at 26 and 21. The crude alkenyl succinic anhydride product from the flash evaporator was passed to still 30 where it was distilled at 150 to 200 C. under pressure of about ofthe runs were substantially identical runs had been carried out.

runs was carried out uti' Thereafter cycle 2 of 5 lizing in each run one-fifth of the olens recovered during the rst cycle. Cycle 2 was followed by cycle 3 constituted of four runs in which onefourth -of the olens recovered during cycle 2 were employed in each run. In cycle 5, two runs were made, each run utilizing one-half of the oleiins recovered during cycle 4, and cycle 6 involved one run in which al1 the oleiins recovered during cycle 5 were employed. For each run suiiicient maleic anhydride was introduced into thev autoclave to furnish about 15 per cent by weight of the autoclave charge. In cycles 4, 5 and 6 a reaction period of three hours at 225 C. was employed. Otherwise, all carried out in substantially the same manner. The .following tabulation is a 'summary of the results obtained during the twenty-one runs constituting the six-:cycles (parts are given by welght) Cycle No.ofruns per cycle 6 5 4 3 2 1 Reaction time, hours 2 2 2 3 3 3 Autoclave input:

Hydrocarbons 102.40 85.86 72.33 59.76 50.12 41. 96 Maleicanhydride 18.08-16.31 13.93 11.88 9.52 7.97 Autoclave output;

Sepatatedgum 3.26 .19' .15 .00 .00 .00 Remalnder 115. 73 100.78 85.00 70.61 58.44 48.96 Flash evaporator:

'Input-v 11573100.78 85.00 70.61 58.44 48.9

Recovered hydrocarbon with dissolved anhyi dride 86.80 73.11 60.70 50.66 42.36 36.66 Recovered maleic anhydr e 0.10 2.92 1.`57 1.29 0.52 0.85 Still 30: i

In ut 28.22 23.20 22.25 18.38 15.16 10.98 Al enyl succinic anhydrdes 24.50 19.40 18.22 15.20 13.54 9.14 Stilltesidue 3.07 3.52 3.66 2.54 1.52 1.55

largely in the first cycle. i. e., the recycled hy-` drocarbons tended to form little or no gum. By utilizing a reaction mixture containing about per cent by weight of hydrocarbon and about-15 per cent 'by weight of maleic anhydride and completely dissolving the anhydride in the hydrocarbons at about 175 C. before heating the reaction mixture to 225 C., the reaction proceeded smoothly and rapidly at the higher temperature at relatively uniform pressures. Sharp increases inl pressure within thel autoclave such as take place when a mixture of olenic hydrocarbons and undissolved maleic anhydride are heated under pressure above 200 C. did not occur.

` Instead of storing the olefin stock recovered from condenser 24 until the end of the plurality of runs before recycling it'to the autoclave, 'it may be desirable in many cases to recycle the recovered hydrocarbons directly t0 the .receiver 5 and thence together with freshly `distilled 01enic petroleum hydrocarbons into the succeedinstead of two' andere Example 2 This is an example of the continuous process employing the arrangement of apparatus disclosed in Figure 2. A mixture of the freshly distilled olefin stock hereinabove described in Ex- 'ample 1', and recycled olefin stock containing a little dissolved maleic anhydride is continuously pumped from reservoir 35 to dissolver 4i and molten maleic anhydride is pumped tothe dissolver from reservoir 31 in proportions to maintain a ratio of about 85 parts by weight of hydrocarbons to parts by weight of the anhydride in the dissolver. The dissolver is maintained at about 175 C. and under a pressure of from 200 to 275 pounds per square inch and continuous circulation of the hydrocarbons and maleic. anhydride therein is secured by the operation of pump 43. The' small amounts of gum which form in the dissolver tend to settle to the bottom thereof and are removed from time to time through valved outlet 02. A solution of about 15 parts by weight of the anhydride and about 85 parts by weight of the hydrocarbons is continuously introduced from the dissolver 'into reactor 50 which is maintained at a temperature of about 225 C. and under pressure of from 200 to 275 pounds per square inch, the rate of introduction being regulated so the passage of the still 60 amounts to about 440 parts by weight. By utilizing` freshly distilled oleiins, the formation of gum in the reactor 50 is maintained low. usually not above about 2 per cent based on the total weight ofthe reactants. Furthermore. by completely dissolving the maleic anhydride in the hydrocarbons before introducing them into the reactor, smooth, rapid reaction ofthe maleic anhydride with the olefins is continuously accomplished without sharp increases in pressure which are experienced when mixtures of undissolved maleic anhydride and mixed olefins of cracked petroleum origin are heated above 200 C.

Thus it will be seen that the invention provides an improved process for reaction of mixed aliphatic mono-olefins with maleic anhydride rapidly and smoothly at relatively high temperatures with reduced waste of reactants due to side reactions resulting ingum formation. In the claims, the expression "freshly distilled olenl I mixtures or the equivalent is used to describe oleiin mixtures which are distilled and are then, prior to substantial formation of gummy materials and oxyggi compounds, reacted with maleic anhydride. Under ordinary commercialco'nditions in which the distilled olefins are placed,

' inv metal containers they should be used within mixture through the reactor requires about 3 hours. The reaction mixture from the reactor is continuously ldischarged to flash evaporator 56 at 63, cooled and filtered to separate maleic any hydride crystals and discarded. T he remainder A of the hydrocarbons containing a little dissolved maleic anhydride is recycled to reservoir 35.- Thev unvaporized material including alkenyl succinic anhydrides, gums, etc., passes from the flash evaporator to still 66 where the anhydrides are distilled off under reduced pressure, e. g., `10 to 30 millimeters of mercury, leaving the gum and other non-volatile material in the still asresidue.

The alkenyl succinic anhydride vapors are condensed in condenser 61 'and the condensate is fractionally distilled in still 68 under pressure of 10 to 30 mm. of mercury to separate maleic anhydride and olefins therefrom leaving the desired anhydrides as still residue. The vapors from still 68 are conducted to condenser 10 operated under pressure of' about 10 to 30 mm. of mercury at 0 C. wherethe maleic anhydride and hydrocar- 'bons are condensed. The anhydride and hydrocarbons. are separated from non-condensable gases in separator 12 and pumped to separator from which they are recycled to reservoirs 35 and 3l.

perating in accordance with this example, the production of 2,000 parts by weight of alkenyl succinic anhydrides requires about 1850 parts by weight of the olefln fraction and about 1285 parts'by weight of maleic anhydride. During the reaction about 685 parts by weight 'of hydrocarbons'cont'aining alittle dissolvedmaleic anhydride are bled of! at 83 and the residue from about a few days after distillation is effected; storage for longer periods is likely to result in formation of gums and oxygencompounds which materially reduce the maleic anhydride efficiency. In somecases the period between distillation and use of .the olens may be somewhat prolonged by adding to the distilled olefins a gum and oxidation inhibitor such as diphenylamine, particularly if the olefins are kept in glass and not metal containers.

Since certain changes may be made without departing from the scope of the invention, it is intended the above shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A process for the synthesis of alkenyl succinic anhydrides from maleic anhydride and cracked -petroleum hydrocarbon mixtures containing mono-olens, which comprises distilling the cracked petroleum hydrocarbon mixture to obtain a product free from gums, oxygen compounds and water, mixing the freshly distilled product with an amount of maleic anhydride' equivalent to'5% to 20% by weight of the resulting mixture; the amount of maleic anhydride being not in excess of that which will dissolve in the hydrocarbon mixture at a temperature between 150 and 200 C., completely dissolving sai'd maleic anhydride in said hydrocarbon mixture by intimately commingling these ingredients' at a temperature within the range of 150q to 200 C. for a time up to about two hours, then raising the temperature of the resultant solution to between 200 and 250 C. under suiiicient pressure `to -maintain the olefins in a liquid phaseto bring 4about reaction between the maleic anhydride vand olefins, and recovering the alkenyl succinic anhydride product. y

2. A process for the synthesis of alkenyl succinic anhydrides from maleic anhydride and cracked petroleum hydrocarbon mixtures containing mono-olefins. which comprises 4distllling the cracked petroleum hydrocarbon mixture to obtain a product free from gums', oxygen compounds and water, mixing the freshly distilled product with an amount of rriaieicanhydride equivalent to 5% to 20% by weight of the result'- ing mixture. the amount of maleio'anhydride .9 being not in excess of-that which will dissolve in the hydrocarbon mixture at a temperature between 150 and 200 C., completely dissolving said maleic anhydridein said hydrocarbon mixture by intimately commingling these ingredients at a temperature within the range of 150 to 200 C. for a time between about 0.5 and aboutv 2 hours, then raising the temperature of the resultant solution to between 200 and 250 C. under suicient pressure to maintain the oleiins in a liquid phase to bring about reaction between the maleic anhydride and olefins, and recovering the alkenyl succinic anhydride product.

3. A process for the synthesis of alkenyl succinic anhydrides from maleic anhydride and cracked petroleum hydrocarbon mixtures containing mono-olens having from 4 to 25 carbon atoms per. molecule, which comprises distilllng the cracked petroleum hydrocarbon mixture to obtain a product free from gums, oxygen compounds and water, mixing the freshly distilled product with an amount of maleic anhyequivalent to from 5% to 20% by weight of the mixture, the amount of maleic anhydride being not in excess of that which will dissolve in the dride equivalent to 5% t`o'20% by weight of the resulting mixture, the amount of maleic anhydride being not in excess of that which will dissolve in the hydrocarbon mixture at a temperature between 150 and 200 C., ycompletely dissolving said maleic anhydride in said hydrocarbon mixture by intimately commingling .these ingredients at a temperature within the range of150 to 200 C. for a time between about 0.5

and about 2 hours. then raising the temperature.-

of the resultant solution to between 200 and 250 C. under sufcient pressure to maintain the olens. I

in a-liquid phase to vbring about reaction between hydrocarbon mixture at a temperature between about and about 200 C., continuously dissolving said maleic anhydride in said hydrocarbon mixture by intimately commingling these ingredients at a temperature between about 150 and 200 C. for a time up to'about two hours, continuously passing the resultant solution through a reaction zoneat la temperature of from 200 to 250 C'. under sufficient pressure to maintain the olens in a liquid pbase to bring about reaction between the maleicanhydride and olefins, continuously withdrawing the reaction mixture from the reaction zone, separating unreacted olefins and maleic-anhydride from the alkenyl succinic anhydrides formed during the reaction, and utilizing at least a por,- tion' of the. unreacted olens "thus recovered together with additional mono-olens for the dissolution of additional maleic anhydride.

MEARL A. insu. ROBERT F. ENGLE. 

